This study investigates the potential interaction between nevirapine (Viramune), abacavir and amprenavir and the effectiveness of this combination therapy in HIV-1 infected antiretroviral naive adults. The main purpose of this study is to evaluate the interaction between the drugs nevirapine (a non-nucleoside reverse transcriptase inhibitor, NNRTI), abacavir (a nucleoside reverse transcriptase inhibitor, NRTI) and amprenavir (a protease inhibitor, PI) and also look at the long-term effect of this combination of drugs on the amount of virus in the blood. Nevirapine, abacavir and amprenavir are FDA-approved drugs, however, the use of these drugs in combination is investigational.